Description

WARNING:Xst:3149 - Value "1" of property "syn_preserve" is not applicable.
WARNING:Xst:3149 - Value "1" of property "syn_preserve" is not applicable.

Solution

These warnings occur with the new XST parser for Virtex-6, Spartan-6, and later architectures.
 

The reason is that the attribute "syn_preserve" is being set to 1 as outlined in the Synplify user documentation.

/* synthesis syn_preserve=1 */;

/* synthesis syn_preserve=TRUE */;

WARNING:Xst - Value "1" of property "syn_preserve" is not applicable. List of valid values is "true, false, yes, no"